The sea transport of dangerous goods are regulated by the IMDG Code. In the Baltic sea area many crossing use the MOU (Memorandum of Understanding), which allow various exemptions from the IMDG Code using the ADR regulation for classification, marking and segregation to some extent. Among the MOU exemption are the segregation relaxation where categories 1 and 2 are exempted under LWHA (Low Wave Height Area).

Instead of the stowage categories in the IMDG Code, MOU use a more general approach in a table where each class/packing group/flashpoint have there own stowage category. The passenger limitation is also increased by 1 per 1 meter ship length instead of 1 per 3 meter in the IMDG Code.

The use of MOU is automatic granted if the ship has a Document Of Compliance according to SOLAS.  

ADR 1.1.3.1a is exempted again in MOU version 2023.